Illuminated dials



R. T. KILLMAN ILLUMINATED DIALS Filed Sept 1'7 1953 Feb. 19, 1957 ROBERT T. KILLMAN INVENTOR 2 2 ATTORNE YS United States Patent ILLUMINATED DIALE Robert T. Killman, Baltimore, Md., assignor to llendix Aviation Corporation, Towson, Md., a corporation of Delaware Application September 17, 1953, Serial No. 3%,723 3 Claims. (Cl.116-124.4

This invention relates to illuminated dials and in particular, to self-extinguishing illuminated dials for television applications.

The customary procedure when viewing television is to decrease the light intensity of the room as this reduces eye fatigue. Under these circumstances, difficulty is experienced in discerning the numerals on the channel selector dial when changing stations unless a constant source of illumination is provided or the illumination in the room is momentarily increased. To provide a mode of panel lighting that would be constant and unshielded would be disturbing to the viewer, while a manually controlled switch or a shielding over for a dial light would be inconvenient.

It is therefore an object of this invention to provide a means for temporarily illuminating the numerals on a television selector dial such that station selections may be properly made in a semi-darkened or darkened room.

It is another object of this invention to provide such 7 a means which will not present an objectionable source of illumination after channel selection has been completed.

These and other objects and advantages are realized in an arrangement in which a dial, having numerals made from a phosphorescent material formed therein or there-- on, has a mask mounted in the front thereof such that all of the numerals, except for the one indicating the selection, are obscured from the viewer. A source of light is so arranged that all of the numerals, except for the one indicating the selection, are exposed thereto. When a new selection is made by moving the dial to a new posi tion, the numeral identifying the new selection is one that has been exposed to the source of light and because it is constructed from a phosphorescent material, it will glow for a short length of time after the selection has been completed. The after-glow characteristic of the phosphorescent material is such that sufiicient illumination of the numerals is provided for the proper selection of the channels.

Referring to the drawings:

Fig. '1 is a front view of a dial lighting system embodying the invention; and

Fig. 2 is a sectional elevation view of the system in Fig. 1 taken through the line 22.

Considering Fig. '1, .there is 'shown a panel 1 in which there is mounted a dial-2 having spaced about its periphery channel identifying numerals 3. A knob 4 is provided for selecting diiferent channel positions. The position chosen is indicated by the appearance of a numeral 3 in a window 5 of the panel 1.

Fig. 2 is a sectional view of the system of Fig. 1. A shaft 6 has secured thereto the knob 4, the dial 2, and a tuner 7. A lamp 8, with its associated wire leads 9, provides energy for illuminating the numerals 3 that are not visible through the window 5.

The window 5 is constructed so that, as seen from the front of the panel 1, only the numeral 3 that indicates the channel selection is visible while the illumination from the lamp 8 is not visible. Impinging upon the numerals 3 that are not within the window 5 is energy from the lamp .8. Because the numerals 3 are constructed from a phosphorescent material, they will become luminous when energized by the lamp 8. When the channel position is changed, one of the numerals 3 that have been exposed to the lamp 8 will appear in the window 5 while the numeral 3 corresponding to the previous selection is removed. The phosphorescent characteristic of the numeral 3 causes it to glow for a short time after the energy from the lamp 8 has been. removed. The phosphorescent material is chosen such that its after-glow characteristic is of a sufiicient duration to permit the operator to discern the numeral 3, but not of sufiicient duration to present an annoying source of light to the viewer of a selected program.

Although a television dial assembly was used as an illustration of the invention, it is obvious to those skilled in the art that it is possible to have various embodiments of the invention which are not associated with television.

What is claimed is:

l. A visual indicator comprising a first member having at least one index aperture; a second member carrying visibly phosphorescent indicia arranged to register with said index aperture to indicate the relative positions of said first and second members, said indicia being concealed by said first member except at said index aperture; a source of radiant energy for exciting at least one of said phosphorescent indicia which are hidden from view by said first member; and shielding means associated with said aperture for preventing excitation of an indicium registered with said index aperture.

2. A system for the temporary indication of the position of a dial, comprising: a plurality of indicia of phosphorescent material on one face of said dial; a panel; said dial being mounted behind and adjacent said panel; said panel having a window formed therein of such size and location that one and only one of said indicia is visible therethrough at one time; a source of energy capable of exciting said phosphorescentmaterial to luminescence; said source being so positioned that energy therefrom impinges on the said indicia; means associated with said window to shield from said energy the said one of said indicia visible through said window; and means for effecting the rotation of said dial.

3. A system for the temporary indication of the position of a channel selecting means of atelevision receiver; said system comprising: a dial rotatably driven by said means; a plurality of numerals of phosphorescent material 7 on one face of said dial; a panel; said dial being mounted behind and adjacent said panel; said panel having a window formed therein; said window being so located in said panel that one and only one of said numerals is visible therethrough; a source of radiant energy capable of exciting said phosphorescent material to luminescence; said source being so positioned that energy therefrom illuminates said numerals; and means associated with said window shielding the said one numerals visible through said window from said energy.

References Cited in the file of this patent UNITED STATES PATENTS 

